1. Field of the Invention
The present invention relates to a disk driving apparatus for recording and reproducing information in and from a disk-shaped recording medium such as a hard disk. In particular, the present invention relates to a disk driving apparatus with enhanced impact resistance.
2. Description of the Related Art
Hard disk driving apparatuses (simply called “disk drives” below) have been reduced in size, but improved in memory capacity. Recently, such a disk drive is employed as a storage unit in a mobile PC, and also as a recording unit for music, voice or images in a portable music player or a video camera (see Patent document 1 below).
Typically, a hard disk drive includes one or more disks rotatable at high speed, and a head that is held in contact with or slightly spaced from the disk surface (see Patent document 2 below). The head is supported by a head actuator for performing “seek” with respect to the disk.
As known in the art, the disk drive has a merit of quick access, in addition to the compactness and large recording capacity mentioned above. On the other hand, the disk drive is rather vulnerable to an impact due to the supporting structure: the head actuator is held in direct contact with or slightly spaced from the disk surface for information writing or reading. If a big shock is given to the hard disk drive when the head is on or adjacent to the disk, the head may collide with the disk, thereby destroying the data stored in the disk, or damaging the recording layer of the disk.
The impact resistance of the disk drive may be improved as the mass of the head actuator becomes smaller. Another way to improve the impact resistance of the disk drive is to increase the rigidity of a suspension used for urging the head toward the disk, or to strengthen or lighten the head actuator itself. It has been proved, however, that none of these measures is sufficient for absorbing a shock occurring when the disk drive falls onto the ground. There are some types of disk drives which are provided with a built-in acceleration sensor for detecting a fall of the apparatus. In such a disk drive, when the falling of the disk drive is detected, it is possible to move the head away from the disk. This system, however, requires an additional cost for the acceleration sensor and a control circuit associated with the sensor. Further, the system may be ineffective when the shock is inflicted too fast, i.e., before the system executes the control.
Patent document 1: JP-A-2004-206768.
Patent document 2: JP-A-2005-32395.